The overall objectives for this Core are to provide the required experimental animals and support services needed to facilitate the AIDS vaccine development studies proposed in Projects 1-3 in this application. This will include provision of 2-3 year old retrovirus-free (SIV, STLV-1, SRV) and herpes virus B-free rhesus macaques from the Yerkes macaque breeding colonies; immunization of the animals with Vaccine Vectors as detailed in Projects 1 and 2; viral challenges of selected immunized animals; daily monitoring of the experimental animals; periodic physical examinations and blood collections from the experimental animals to assess the animals' clinical and physical condition and to provide specimens for laboratory evaluations (Projects 1-3); performance of CBCs and flow cytometry evaluations to determine lymphocyte subsets; real time RT-PCR determinations to evaluate viral load in the plasma of immunized and challenge animals; and the performance of complete gross and histologic evaluation of all experimental animals that die or that are sacrificed during the course of the study. Provision of these resources and support services will facilitate the development and testing of live viral vectors as candidate AIDS vaccines as described in Projects 1-3 of this application. The proposed virologic and clinicopathologic evaluations in concert with immunology core studies will allow assessment of vaccine efficacy with respect to vector replication, immunogenicity and prevention of infection or modification of post-challenge virus load or viral set point.